A Review of the Application of Stainless Steels in Desalination Equipment

This study presents the first systematic investigation into the coupled effects of temperature, pH, and ion concentrations (Fe 3+ , Cl − , and NO 3 − ) on the electrochemical corrosion behavior of S31254 austenitic stainless steel in simulated flue gas condensate. Advanced electrochemical techniques—including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis—were employed to evaluate corrosion performance under varying conditions. Results indicate that both elevated temperature and low pH significantly destabilize the passive film, thereby reducing corrosion resistance. At 60 °C, Fe 3+ ions notably accelerate corrosion due to their strong oxidizing nature and influence on anodic polarization. In contrast, Cl − and NO 3 − ions exhibit relatively minor effects under the tested conditions, which is unexpected given the commonly aggressive behavior of chloride ions. These results reveal complex environmental interactions influencing the passivation and corrosion behavior of stainless steel in flue gas environments. The findings offer valuable insights into the corrosion mechanisms occurring in flue gas desulfurization (FGD) systems and emphasize the need to consider synergistic environmental factors. This study contributes to the development of more effective corrosion mitigation strategies, thereby supporting the long-term durability and safe operation of exhaust gas treatment facilities.

This study applies statistical approaches utilizing linear regression and artificial neural networks (ANNs) to predict the corrosion behavior of austenitic stainless steels (316L, 904L, and AL-6XN) under various environmental conditions. The environmental variables considered include temperature (30–90 °C), chloride ion concentration (20–40 g/L), and pH (2–6). Analysis of variance (ANOVA) confirmed that the input variables, including the Pitting Resistance Equivalent Number (PREN ranging from 24 to 45), significantly affect the critical pitting potential. The influence of the variables was ranked in the order: PREN, temperature, pH, and chloride ion concentration. A linear regression model was developed using significant factors and interactions identified at the 95% confidence level, achieving a predictive performance with R2 = 0.789 for critical pitting potential. To predict potentiodynamic polarization curves, an ANN based on supervised learning with backpropagation was employed. The ANN model demonstrated a remarkably high predictive performance with R2 = 0.972 in complex corrosion environments. The predicted polarization curves reliably estimated electrochemical characteristics such as corrosion current, corrosion potential, and pitting potential. These results provide a valuable tool for predicting and understanding the corrosion behavior of stainless steels, which can aid in corrosion prevention strategies and material selection decisions.

The application of a bipolar electrochemistry technique to simulate the galvanic corrosion behaviour of dissimilar stainless steels is introduced. The technique allows comparison of the bipolar response by controlling the extent of localised corrosion as a function of an applied offset potential. The setup was explored to simulate the galvanic performance of type 420 ferritic and type 304L austenitic stainless steels, yielding information about the anodic vs. cathodic behaviour of these materials when in close proximity to each other. The introduced approach provides a novel methodology for simulating the galvanic corrosion behaviour of stainless steels.

Influence of the irradiation on the corrosion behavior of stainless steel (type 304ULC) in boiling nitric acid solution was examined by using 60Co γ-ray source. It was found from the experimental results that radiolysis products of nitric acid (NOx, HNO2) resulted from the γ-ray irradiation made the environment in the bulk solution more reducing one. On the other hand, corrosion rate of 304ULC was slightly enhanced by the irradiation, which being trivial from the engineering viewpoint. From the result of an AC impedance measurement, this corrosion enhancement was inferred as caused by an enhancement in the current across the passive film by the γ-ray irradiation on the stainless steel surfaces.

Influence of the irradiation on the corrosion behavior of stainless steel (type 304ULC) in boiling nitric acid solution was examined by using 60Co γ-ray source. It was found from the experimental results that radiolysis products of nitric acid (NOx, HNO2) resulted from the γ-ray irradiation made the environment in the bulk solution more reducing one. On the other hand, corrosion rate of 304ULC was slightly enhanced by the irradiation, which being trivial from the engineering viewpoint. From the result of an AC impedance measurement, this corrosion enhancement was inferred as caused by an enhancement in the current across the passive film by the γ-ray irradiation on the stainless steel surfaces.

High-temperature corrosion behavior of austenitic stainless steel in quaternary nitrate molten salt nanofluids for concentrated solar power

The studies on the corrosion behaviors of 316NG and 304NG nitrogen-containing stainless steels made in China

With good pricing, high strength, as well as corrosion resistance, stainless steel is a widely used and popular choice for many applications as a rust resistant material, however many types of corrosion attack stainless steel, such as pitting and crevice corrosion, intergranular corrosion, stress-corrosion cracking, hydrogen embrittlement, general corrosion, and attack by high-temperature gases. This article reviews the corrosion mechanisms of stainless steel to understand the corrosion behavior of stainless steel which is important for the design of any application. Moreover, this article will provide a platform for selecting the suitable type of stainless steel for any application with high corrosion resistance.

Corrosion of Stainless Steels

Some crown ethers as inhibitors for corrosion of stainless steel type 430 in aqueous solutions

ZG06Cr13Ni4Mo martensitic stainless steel was nitric acid‐passivated to improve its corrosion performance. The effects of nitric acid passivation on the surface morphology, chemical composition, electrochemical properties, semiconductor behavior, and long‐term corrosion performance of the stainless steel were investigated using various analytical techniques. An in‐depth analysis of X‐ray photoelectron spectroscopy (XPS) showed that the passive film formed after the acid passivation process showed high thickness and a duplex character as it consisted of a hydroxide layer and an oxide layer. The oxide layer affected the corrosion resistance and thickness of the passive film. The thickness of the passive film was calculated theoretically as well as experimentally by fitting the electrochemical impedance spectroscopy and XPS results. The electrochemical tests revealed that the dramatic increase in the corrosion resistance of the stainless steel after the passivation was due to the formation of a thick, low‐disorder passive film rather than Cr enrichment. The removal of inclusions resulted in higher pitting resistance, whereas the increased roughness showed a negative effect on the corrosion behavior of the stainless steel. During the wet–dry cyclic tests, the modification of the passive film was examined. The passivated stainless steel exhibited good corrosion resistance for up to 50 days of exposure in the simulated environment.

The comparison of stress corrosion cracking behaviors of four types of commercial austenitic stainless steel in high temperature water was studied. Tests were made at the temperature of 300° and 350°C for 300 hr in an autoclave containing the testing water with 100∼800 ppm of chloride ion added as NaCl. The amount of dissolved oxygen in water was controlled with or without deaeration at the temperatures of 105° and 150°C, respectively. The results were summarized as follows: (1) Neither of the steels showed no stress corrosion cracking provided that the concentration of dissolved oxygen in the testing water did not exceed 0.2 ppm, but cracking was observed on all the types of stainless steel in the water with a concentration of dissolved oxygen higher than 0.3 ppm. (2) Among the solution treated steels, the type SUS 32 was most resistant, and the susceptibility of other types were almost the same. (3) Sensitizing heat treatment markedly increased the susceptibility of cracking for all the types of steels. (4) The cracking was transgranular in the solution treated steels independently of the difference in composition, but the intergranular cracking was also observed in the sensitized type SUS 27 and 32 steels. (5) From the observation on the pitting corrosion formed on the test pieces and also from the metallographic inspection of pits and cracks, it appears that pitting is the cause of initiation of cracking. (6) The results of cracking tests in a boiling 42%MgCl2 aqueous solution did not agree with those in high temperature water in regard to the process of initiation or path of cracking, and also the difference in susceptibility of cracking for the four types of steel was noticed between the two testing methods.

Although pure phosphoric acid is generally known to be mild to austenitic stainless steel, it is corrosive to austenitic stainless steel in some cases. This paper shows the corrosion behavior of stainless steel (mainly 316L) in a low concentration (about 1% H3PO4) phosphoric acid solution at high temperature (about 200°C), and a high concentration (about 33% P2O5) phosphoric acid solution at low temperature (about 70°C).The polarization tests of stainless steels were carried out mainly in 220°C 1% H3PO4 solution with or without dissoluted oxygen. The corrosion rate decreased when Cr or Ni contents in the test specimens increased, but even Hastelloy C-22, Ni-based alloy, did not passivate by itself. Dissoluted oxygen also reduced the corrosion rate of 316L, but no self-passivation occurred.The corrosion behavior of 316L stainless steel in the solution of a phosphoric acid plant was also tested. This solution contained phosphoric acid (33% P2O5), surfuric acid (1.5%), plaster (25%), fluorine ion (2.5%) and so on. It was found that corrosion in the plaster slurry settled from the solution was severer than that in the mixed acid solution without slurry, and the quantity of fluorine ions was higher in the slurry. Thus, it is suggested that CaF2 in the plaster increases the amount of fluoric ions and accelerates corrosion. It is also suggested that ferric ions prevent 316L from corrosion in this environment.

The role of ethanol (C2H5OH) in pitting corrosion behavior of AISI 316L austenitic stainless steel was investigated in aqueous ethanolic solution with chloride. The pitting susceptibility and surface morphology of 316L in a series of ethanol-containing solutions were examined using X-ray photoelectron spectroscopy (XPS), optical microscopy with 3D stitching, immersion tests, and potentiodynamic polarization measurements. Results demonstrated that the ethanol concentration impacted little on the passive film stability while it dramatically influenced the pitting corrosion susceptibility. Corrosion rate of 316L after immersion tests first increased and then decreased as the concentration of ethanol increased from 0 to 10 M in ferric chloride solution. This, however, did not correspond to the breakdown potential which directly decreased from 489 to 249 mV as the water concentration decreased in ethanolic NaCl solutions. The pits density after both immersion and electrochemical tests showed that the initiation of pitting in ethanolic solution tended to occur at multiple points at the same time. The synergy effect on pitting behavior of hydrolysis enhancement and solubility reduction of metal cations due to the introduction of ethanol has also been discussed.

The crevice corrosion behaviour of stainless steel in sodium chloride solution